The previous chapter documented Japan’s interest in financial regionalism in East Asia. This chapter expands the subject from the financial area to East Asian regionalism in general, as the last case study of the book. The chapter analyses how East Asian regionalism has developed since the late 1990s, how and to what degree Japan has contributed to that process, where Japan’s interest in the new East Asian framework lies and what that means to its foreign policy as a whole. Building on the argument developed in the previous chapters, this chapter demonstrates Japan’s increasing initiative in the region, along with its growing interest in East Asia. Also, the way in which Japan has contributed to the development of East Asian regionalism has great significance for the discussion about the style of Japanese foreign policy in the next chapter.